As is known, in some conditions, high-performance cars have great difficulty discharging the power from the engine to the road. In recent years, therefore, a number of major car manufacturers have begun marketing high-performance car models with four-wheel drives.
Besides effectively solving the problem of discharging the power from the engine to the road, such a solution also provides for greatly improving control, road-holding in poor-grip conditions, and therefore intrinsic safety of the vehicle.
Unfortunately, currently marketed four-wheel-drive transmissions have the major drawback of being extremely heavy and bulky, thus creating serious design problems in terms of location within the vehicle and weight distribution over the two vehicle axles. The structure of currently marketed transmissions, in fact, is derived directly from that normally employed in off-road vehicles, in which the weight and bulk of the transmission are considered secondary to strength and simplifying construction.